Spores in Space
Most people know of the Apollo Moon flights that brought American astronauts to the Moon for the first time. But few know that the crew of Apollo 12 brought back stowaway bacteria that had been a contaminant of camera equipment left almost three years on the Moon from an earlier flight. The 50-100 Streptococcus mitisstowawaybacteria had survived the scorching heat of launch, space vacuum, 3 years of radiation exposure, deep-freeze at an average temperature of only 20 degrees above absolute zero, and no nutrient, water or energy source. One way that bacteriacan survive sterile conditions that might otherwise kill it is to encapsulate itself in a protective layer called a spore. Scientists now know from experimental evidence that certain microbes are hardy enough to survive the hazards of space travel such as hitchhiking on a rock that might have been ejected into space following a large bolide impact. Could it then be possible that microbes have “hopped” between the planets or even “seeded” some planets with first life? Astrobiologists say it is a real possibility given that we now know how often planets lose material to space following frequent bolide (big rocks from space!) impacts. In this experiment we will observe how some organisms might survive the harsh conditions of outer space. You will be looking at a more complicated organism than bacteria. You will try to revive Saccharomyces cerevisiae, common baker’s yeast.
1. Write down the necessary ingredients for life.
2. What makes something alive versus something that is not alive?
3. Look at your yeast spores in your bag. Write three observations of the dry yeast below.
(color, smell, size, etc.)
4. Now add a little water to the bag and add a sugar cube. Squeeze the air out of the bag and seal it. Observe what happens and write what you observe below.
5. Afteryou see some changes,open the bag slowly and observe any new changes. Write what you see then throw away the bag.
Now answer the following question as best you can.
a. What conditions were necessary to revive the yeast?
b. What gas was produced in the bag? Why was this gas produced?
c. Describe the process of respiration in organisms (eating produces wastes including gasses).
d. How might yeast survive the sterile conditions of being stored for long times at the supermarket or in you home?
e. What kind of organism is yeast? What kind of cell do these organisms have (prokaryote or eukaryote)?
f. What advantage might yeast have in potentially making a long exposed space flight?
Now do the two questions of the Section 6 Assessment on page 579 in your textbook. You can write your answers on the back of this paper or on a separate sheet of binder paper.